Real Reason Bristol Palin, Levi Johnston Split?

Just three weeks after announcing their surprise second engagement, Bristol Palin and Levi Johnston have reportedly split up.

The question is -- why?

It looked as if Bristol and Levi had settled down and were ready to raise their year-old son, Tripp, together, as a married couple. Now, Bristol says that's all changed and she's called off their engagement.

Pictures: Splits

CBS News National Correspondent Jeff Glor said on "The Early Show" it was a picture that was hard to believe, Levi and Bristol, back together after a year-and-a-half-long public feud. The pair, with their infant son, announced their engagement just three weeks ago in US Weekly.

Bristol told reporters, "He got down on one knee and asked me to marry him."

But not long after, Bristol told People magazine there was trouble.

Betsy Gleick, Peopl's executive editor, said to CBS News, "What Bristol told People is that, on the very day that the world learned they were going to get married, Levi came home and said to her that he may have gotten another woman pregnant."

Bristol said in People that the final straw came when Levi was spending more time trying to get a reality show than being a father. She said, "He's just obsessed with the limelight and I got played."

Gleick told "The Early Show", "Bristol is heartbroken. She described texting him and getting no answer, and then eventually she said Levi said, 'Hey, do you want to be on a reality show?"'

Bristol, however, says she wants no part of Levi's reality show plans. In a statement to People.com, her mother, Sarah Palin, even weighed in, saying, "I wish for Bristol to be able to move forward in life with her same forgiving, gracious, optimistic spirit, but from henceforth she'll know to trust but verify. Bristol is strong, she is independent, and she knows what is right for her son."

Glor added on "The Early Show" that Bristol has reportedly moved back in with her parents -- on their orders. As for Johnston, Glor reported he is shooting a music video in Los Angeles in which he plays a lover whose romance is thwarted by his girlfriend's disapproving mother.

On "The Early Show", Bonnie Fuller, editor in chief of Hollywoodlife.com, said the engagement isn't a stunt. The couple actually had a reality show on the table for $1.5 million, she said, and they walked away from the offer.

Fuller said the producer told Hollywoodlife.com that the show couldn't go forward without an entire family -- Bristol, Levi and Tripp -- on board.

"There was no interest in just Levi on his own," she said.

Fuller added the producer was very surprised by the split, saying the producer sent someone to Anchorage to talk to them, and suddenly, Fuller said, "they disappeared."

Fuller said, "Suddenly, he's off in L.A. and his people are claiming that he's got all kinds of other offers on the table."

So, is this the real end of Bristol and Levi?

Fuller said, "They are 19 and 20 years old, very young. You know, teenagers get together and break up all the time. And I think he particularly is very immature and he's in love with fame. He's in Hollywood right now, talking to people, at parties, filming a music video -- supposedly mocking her family -- though he's denying that, but he did film it."

What about Baby Tripp?

Child psychologist and "Early Show" contributor Dr. Jennifer Hartstein said, "One of the main victims is Tripp, is this little boy whose dad is in and out and in and out of his life. There is no stable presence. It's very confusing for a 19-month-old to understand what that's like. That's really going to be confusing for him down the road. ... They'll have to find positive people to be in his life to take the place (of his father)."

"Early Show" co-anchor Erica Hill pointed out Bristol told People magazine she feels trapped.

Hartstein said, "Absolutely. She's 19. She's isolated. She's working. She's taking care of this child. What friends of hers are in the same place? Who has kids like she does? She can't go out and just hang out. It's a really tough position. She's not in the same typical 19-year-old position as her girlfriends and friends may be."

Fuller added, "I think (Bristol) does feel trapped and she looked at this as an escape. The fact Levi didn't sell a show and came back into her life, she was looking to create a stable family. Then she made money by selling their engagement story to the magazine. And there was all this other money. It was an escape, a way out. Now she's moved back with her parents."

Hartstein said Bristol is looking for someone for support and help her.

She said, "Why do we always go back to old relationships? They don't always change but we go back because we know them. The devil we know is better than the devil we don't. She needs to learn to grow out of that need and be self-reliant and find the best person for her."